This invention is based on and claims priority to Japanese Patent Application Nos. 2001-038202 and 2002-013828, filed Feb. 15, 2001 and Jan. 23, 2002, respectively, the entire contents of which are hereby expressly incorporated by reference.
1. Field of the Invention
This invention relates to a control system for an engine of a watercraft.
2. Description of Related Art
Personal watercraft have become very popular in recent years. This type of watercraft is quite sporting in nature and carries one or more riders. A hull of the personal watercraft commonly defines a rider""s area above an engine compartment. An internal combustion engine powers a jet propulsion unit that propels the watercraft by discharging water rearward. The engine lies within the engine compartment in front of a tunnel, which is formed on an underside of the hull. The jet propulsion unit is placed within the tunnel and includes an impeller that is driven by the engine.
A deflector or steering nozzle is mounted on a rear end of the jet propulsion unit for steering the watercraft. A steering mast with a handlebar is linked with the deflector through a linkage. The steering mast extends upwardly in front of the rider""s area. The rider remotely steers the watercraft using the handlebar.
The engine typically includes at least one throttle valve disposed in an air intake passage of the engine. The throttle valve regulates the amount of air supplied to the engine. Typically, as the amount of air increases, the engine output also increases. A throttle lever or control is attached to the handlebar and is linked with the throttle valve(s) usually through a throttle linkage and cable. The rider thus can control the throttle valve remotely by operating the throttle lever on the handlebar.
In accordance with one aspect of the present invention, a jet propelled watercraft comprises an engine having at least one throttle valve. The throttle valve is movable between an idle position and a fully open position. A throttle operator, which is remotely positioned relative to the engine and is coupled to the throttle valve, is movable between first and second positions. This movement of the throttle operator causes the throttle valve to move between the idle and fully open positions, respectively. An engine control system comprises a first sensor configured to detect an operating state of the watercraft or the engine, a second sensor configured to detect a position of the throttle operator, and a throttle valve control mechanism that includes an actuator which cooperates with the throttle valve under at least one operating state of the watercraft or the engine. A controller of the engine control system communicates with the first and second sensors and with the throttle valve control mechanism. The controller is configured to activate the throttle valve control mechanism once the operating state of the watercraft or engine is greater than a predetermined state. The controller is also configured to leave active the throttle valve control mechanism at least when the throttle operator quickly moves to the first position so as to maintain the throttle valve between the idle and fully open positions.
In accordance with another one aspect of the present invention, a jet propelled watercraft comprises an engine having at least one throttle valve. The throttle valve is movable between a closed position and a fully open position, A throttle operator is remotely positioned relative to the engine and is coupled to the throttle valve. The throttle operator can be moved between first and second positions which cause the throttle valve to move between the closed and fully open positions, respectively. An engine control system cooperates with the engine to control engine speed under at least one operating condition of either the watercraft or the engine. The control system comprises a first sensor configured to detect an operating state of either the watercraft or the engine, a second sensor configured to detect a position of the throttle operator, a throttle valve control mechanism that includes an actuator selectively cooperating with the throttle valve under at least one operating state of the watercraft or the engine, and a controller communicating with the first and second sensors and with the throttle valve control mechanism. The controller is configured to activate the throttle valve control mechanism once the operating state of either the watercraft or engine is greater than a preset state, and the controller and throttle valve control mechanism are further configured to delay closure of the throttle valve at least when the throttle operator quickly moves to the first position.
In accordance with yet another aspect of the present invention, a method of controlling a watercraft having an engine is provided. The method involves sensing a first control parameter that is indicative of the operating state of either the watercraft or the engine, sensing a position of an operator used to control engine speed to determine at least when the operator is abruptly moved to an idle position, and activating a throttle valve control mechanism when the operating state of the watercraft or engine is greater than a preset operating state. Engine speed is maintained above an idle speed when the watercraft or engine is operating above the preset operating state and the operator is abruptly moved to the idle position.
Further aspects, features and advantages of this invention will become apparent from the detailed description of the preferred embodiments which follow.